Abstract: Embodiments for generating a reservoir performance forecast are provided. The embodiments may be executed by a computer system. In one embodiment, a method includes obtaining inflow performance relationship data generated from a physics-based subsurface-surface coupled simulation model having a surface, a subsurface, and one or more wells fluidly connecting the subsurface to the surface. The inflow performance relationship data comprises performance data for at least one phase of fluid for each well. The method also includes generating a performance forecast for the reservoir using a subsurface simulator and a surface simulator. The subsurface simulator uses the inflow performance relationship data to represent the subsurface during generation of the performance forecast, and the performance forecast satisfies constraints solved by the surface simulator. In one embodiment, a method does not utilize a surface simulator.